Betamethasone May Damage Brain of Growth-Restricted Fetus

Drug used in sheep study to promote lung maturation caused damage to fetal hippocampus

THURSDAY, March 8 (HealthDay News) -- Intrauterine growth-restricted fetuses given antenatal glucocorticoids to promote maturation of the lungs may be at increased risk of brain damage, according to the results of a study in sheep published in the March issue of Endocrinology.

Euan M. Wallace, M.D., of Monash University in Victoria, Australia, and colleagues conducted a study in sheep pregnant with twins. The size of one of the fetuses was restricted by ligation of the fetus's umbilical artery while the other twin was used as a control. Five of the ewes received betamethasone while four received saline on two consecutive days after surgery.

Carotid blood flow in the control fetuses decreased 3.5 hours after the first dose of betamethasone was administered, before returning to baseline at the 5.5-hour mark. However, in restricted-growth fetuses, carotid flow declined by a similar amount as in the control fetuses, but shot 25 percent over baseline, peaking at 11 hours.

All treatment groups had increased oxidative damage in the fetal hippocampus and subcallosal area compared to the control fetuses. "There was a significant correlation between carotid blood flow reperfusion after betamethasone and the number of 4-hydroxynonenal-positive cells in the cortex and hippocampus," the authors conclude. "These data suggest that antenatal betamethasone may induce brain injury in the intrauterine growth-restricted fetus but not in the normally grown fetus."

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